Metallic strips, sheets and formed parts are produced in very large numbers and must be protected against corrosion. In certain production processes, however, metallic substrates coated with at least one paint film have the disadvantage of displaying inadequate corrosion protection if the coatings are thinner than 30 μm, for example. To date, to the knowledge of the applicant, no adequate corrosion-resistant high-speed coating process for coating with a single thin, polymeric, chromate-free, corrosion-resistant coating is known which allows adequate corrosion protection.
Furthermore, to the knowledge of the applicant there is to date no so-called pretreatment primer in industrial use, wherein a thin, e.g. 5 to 15 μm thick, paint film or a thin, paint-like organic film having elevated corrosion resistance is applied directly to the metallic surface without the application below it of a pretreatment coating or a similar coating, in particular for increasing paint adhesion and corrosion protection.
DE-A1-196 23 268 describes a powder coating composition wherein a comparatively high content of an organic corrosion inhibitor is used together with an inorganic corrosion inhibitor.